This paper is devoting to the relevance of connection between trade union’s legal order and national’s legal order. In particular, considerations are related to representativeness of trade unions in “Protocollo d’intesa 31 Maggio” and in the latest constitutional jurisprudence.

Protocol’s juridical effectiveness towards to nationals industrials unions federations is connected to partecipation’s standards. According to these legal standards trade unions can form craft unions into the company. Sure enough, trade unions are assigned to stipulate Collective Bargaining Agreement.

The A. examines minutely connection between national’s legal order and trade union’s legal order effectiveness.